Multi-granularity switch technologies decrease the complexity of optical cross connects by employing waveband routing and fiber routing techniques. Compared with the traditional wavelength-routed all-optical networks

the routing and resource assignment problem in multi-granularity networks is more complex because of the appearance of waveband tunnel routing and fiber tunnel routing problems. This paper analyzes the architecture of the multi-granularity optical cross connector and proposes the layer graph for routing and resource assignment problem in multi-granularity all-optical networks.